Method of manufacturing forged percussion masonry twist drills



May 20, 1930. i v w PLElsTER ET AL 1,759,416

. METHOD OF MANUFACTURING FORGED PERCUSSION MASONRY TWIST DRILLS v Filed March 24, 1928 2 Shets-Sheet 1 11/ -5/ Wily! 7 3! VENTOR$9 v May 20, 1 930. H. w. PLEISTER ET AL 1,759,416

OF MANUFACTURING FORGED PERCUSSI SONRY TWIST DRILLS 2 Sheets-Sheet 2 Filed March 24. 1928 Fig. 1 is a fragmentary vertical section Patented May 20, 1930 P TENii OFFICE I HENRY w, rLnIs'rnn, OF'WESTFIELD, AND Jonn KARITZKY, or eARwoon, NEW'JER- SEY, Assrerions T HENRY B. NEWHALL CORPORATION, or GARWOOID, NEW Jun SEY, A. CORPORATION OF NEW JERSEY METHOD OF MANUFACTURING FOR/GED PERCUSSION MASONRY TWIST DRILIIS- i Application filed March 24, 1928. Serial No. 264,418.

Our invention relates to the method of manufacturing a forged percussion masonry twist drill.

It further relates to the methodof manufacturing such a forged twist drill which can be economically made from alloys of steel, such as vanadium, chromium or nickel, all of which steel alloys are toodifficult and hard .to economically machine, as is the common that the steel in the flashing'will be of finer texture and thus form a still better quality of steel. Such aforged twist drill will withstand the much more severe duty imposed upon a percussion twist drill, as compared to that required of a steel rotary twist drill. Among other advantages, we obviate, for example, weak spots in an ordinary twist drill, due to machining out ,the'convolutions from a bar of steel and thereby changing the equilibrium of the strains and stresses in the bar which may be perfectly harmless in a ro tary steel drill. Such a machinetwist drill cannot be successfully used as a percussion twist drill in View of the much harder uses to which the drill is put, and the work it has to perform to withstand the multiple blows of ahamlner, or hammer mechanism, which in practice soon cause a machine twist drill to fail. i

. Our invention further relates to certain methods of manufacture and'sub-methods of manufacture, all of which will be more'fully hereinafter described and pointed out in the claims; In the drawings we have shown different embodiments of our invention, but itis,

pf course, to be understood that our invention is not to be confined to these articular embodiments: shown by way of 11 ilStlEttlOI].

upper and lower die blocks.

through an upper and lower die block showing one method of manufacturing the drill blank by forging;

Fig. 2 is a plan view showing the drill lglank removed from theupper and lower die ocki Fig 3 is a plan View of the drill blank of Fig. 2 rotated 90 from the position of Fig. A,

2 and looking down on the. flashing; .Fig. 4 is a plan view of the drillbladewith the flashing removed, l Fig. 5 is a vertical section" on the line 55 of Fig. 4 looking in the direction of the are rows, some of the flashing being dotted in in this figure simply for purposes of clearer description;

Fig. 6 is a perspective View of one form of clurlcomplete forged percussion masonry twist r1 e Fig.7 is an end view of the drill of- Fig. 6 showing the chisel cutting'edge; v I Fig; 8 is a vertical section on the line 88 of Fig. 6;

Fig. 9 is a vertical section showing a modified form of construction;

Fig. 10 is a vertical section showing an other modified form of construction;

' Fig. 11 is'a cross section showing another modification; and i ferent, or modified form of adjustingthe I It is found in practice that ordinary rotary twist drills for cutting steel, in which the spiral grooves are formed by machining a drill rod, will not stand the wear of rough usage of a. masonry percussion drill where the drill is subjected to multiple blows of-a. hammer, or hammer mechanism actuated-by any suitable power. This is partly due to the milling, operation, forming the spiral grooves in the rod, changing the. internal may be perfectly satisfactory for rotary steel work, but is totally unsatisfactory, for work- 1 ing injmasonr under the actuationof reenigma strains and stresses of the steel, thereby form- 7 ing weak spots and weak sections in various parts ofsuch a steel twist drill. Such a drill By our inventionwe cheaply and economically make a forged percussion masonry twist drill in which there are no weak spots, orweak 7 sections, due to changing the internalstrains and stresses of the steel in thefdrill; "but "on the contrary our drill is of uniform toughness and strength throughout, anddevoid of the strains andcounter stra'ins which are in rotarymachine twist drills, and which lead to their failure in the different art to which our invention applies. While werefer to uniformity of quality of steel throughout, it 7 should, of course, be understood, that, as previously pointed out, the texture of the steel at the landsisimproved by its extrusion into the flashing. jIt is "also more economical and r it lstooexpensive to machine out thespiral improves the grain structure toform the concaye fluted section loflour drill 'by. forging than by the m'achinej process.

In the art 'of'ma'sonry drills a twist drill of a hard alloy of steel such as vanadium, chromium or nickel, or similar'hard alloy, would be desirable to obtain the requisite strengthiand rigidity, bnt'it'is not feasible to economically form sucha twist drill because to form a tapering portion 6, this portion,

with the flat surface of the lower die block forming arecess 50.: Thelower. die block 3 has its ineeting surfa'ce 7 eased offjor ta:

' pered at 8 to form a tapered recess51 with the flat surface of the upper die block 1 into which the flashing 10 of the drill blank 11 is forced as the uppendie block 1 and "lower die block 3 arebrought together by suitable mechanism in the forging operation. These 7 recesses -51 are preferably formed a litthe larger than necessary toacco'mmodate ya- I 'riouslengthsof flashing .10-10, for the flashing varies somewhat with d'itferent. drill blanks. It will be'noted that the upper die block 1 is cutaway or eased off'onone side and'the lower die'block is eased offer cut "away on the other side, there being 'a'flat fa ce 'of the opposing die block cooperating with e'ach cut away portion, Fig. 1.

- The convex Portion 2 of the p-P forms a complementary concave [surface 12 the drill blank 11. The convexsurface 4 inthe lower die block 3 forms. the corre spending. concave portion 13 on the lower portion of the drill blank 11 (see These concave portions .12 and 13 'in-theblank form the resulting concave fluted sections which, afterthe drillblade 15 is twisted,

" firm the flutes 11+14 inthe complete forged "twist drillshown in Fig. 6.-

When the drill blank 11 is removed froin the die, its shape is substantially that shown in Figs. 2 and 3. The flashing 1010. is then cut from the drill blank in the ordinary method, forming a and'5).

It will be"noted,'however, that preferably, though notnecessarily, all theflashing is not drill blade 15 (Figs. 4:

removed, shown foriexamplain Fig. 4.

and particularly Fig. 5, the dotted portion in Fig. 5 being that portion of the flashing the flashing 1616 which becomes lands} and permanent parts of the drill blade 15 and of the completed twist drillv 17 shown in Fig. 6.

In this art of masonry drills it is necessary that the drill be turned in the stone, masonry, concrete or other material slowly,

I which is removed. This leaves a portion of g or intermittently, and preferably between eachblow of the hammer or the hammer I mechanism, though, of course, in some hammer mechanisms it is not feasible-to turn the drill partially between the rapid blows of the hammer mechanism, though it is necessary that the drill be'turned to change the position of the cutting edge 18 of the drill between each blow so that new-surfaces of c r the material being drilled will be attacked at each successive blow, and to preventjam ming of the drill within the hole. p

t is therefore desirable to have aradi'al clearance to permit easy turning of'the twist drill within the hole, so-that the chisel-cutting ent surfaces in the hole.

In Figs-5 and 8th'e radial clearances.

19'19 are justlback of the lands 1616. In

the preferred construction the radial clear ances 1919 are arcuate' as more clearly edge 18 (Fig. 6)"wi'l1 be presented todifl'er 7 foo shown in Fig. 8. In the'modification shown in Fig. 9 the radial clearance 20 just back of the land 16 is straight. In Fig; 10 we have shown a modification in which our forgedpercussion masonry twist drill 21 is not provided with a land but is provided with radial j V clearances formed by the arcuate surfaces 22422. just back of the cutting edge 2323 ofjthe drill.

We have shown an another modification.

in Fig. 11 in which our forged percussion masonry twist drill 24 is providedjwith .a

radial clearance by the straight surfaces 25 25 back of the. cutting edges 2626, *therebeing no land'employed in this form. a

By sinking the" twist drill impress-ion diag onally in the upper die block 1 and the lower die block 3 causes the parting line of the dies to c'oincide'with the diagonal line 27' which connects the two flashings 10, 10. This permits theupper and lower die blocks, 1

and 8 respectively" to be readily withdrawn from the'drillblank 11.

It is along this parting line 27, which extends diagonally from one land 16 to the opposite land 16, that thechisel cutting edge 18 is formed by the die blocks '1 and 3'. This diagonal line 27 is the line of greatest diameter and extends diagonally across the end of the drill so that each land 16, 16 forms a part of the chisel cutting edge. The chisel cutting edge 18 being shaped in the die blocks, and being coincident with the parting line of the die blocks, therefore requires but little' grinding to sharpen it, thereby very materially cheapening the cost of manufacture.

Afterthe surplus flashing is removed, a drill blade is formed as shown'in Fig. 4. It is then twisted in any suitable manner to form the flutes 14l 14: as shown in Figs. 6 and 7. The chisel cutting edge 18 is then ground but the amount of grinding is very materially reduced as previously pointed out.

By'our improved method we insure that a given set of upper and lower die blocks 1 and 3 can be employed to make more than one diameter of twist drills. Furthermore, we compensate for wear, or what is technically known as washing, in the impression in the dies 1 and 3. In ordinary forging, when through wear or washlng the impression in the die blocks becomes enlarged to such 7 an extent as to make an imperfect or useless article, the entire face of the die blocks have tobe machined off and a new impression sunk,

or the die blocks have to be thrown away,

either or both of which add greatly to the expense of manufacture.

We obviate this heavy expense, and also permit different size twist drills to be manufactured, with the same set of dies, by setting the upper die block 1 and the lower die block 3 in difierent relation to each other, as for example, that shown in Fig. 12 where the upper die block 1 has been moved to the right somewhat from the position shown in Fig. 1. This will decrease the diameter of the drill blade, and of the twist drill formed from it, because the diameter of the drill represented by line 127 will be some what shorter than the corresponding line 27 in Fig. 5 (on a smaller scale). When the drill blade shown in Fig. 12, is twisted, a

chisel cutting or boring end will be of maxnnum strength, rigidity and toughness and will only require the minimum amount of grinding, trimming off some of the flashing, and twisting the blank.

2. The method of manufacturing a complete integral forged twist masonry boring percussion drill having a chisel cutting or boring end consisting in forging the drill blank and using the flashing to form lands and the chisel cutting or boring edge, said chisel or boring edge including the exterior extremities of the opposed lands, trimming the blank, and twisting it to form the completed twist drill.

HENRY WV. PLEISTER. JOHN KARITZKY.

forged twist percussion drill will be formed somewhat shorter in diameter than the forged twist drill 17 (Fig. 6) for the drill blade 15 (Fig. 4) was formed when the upper and lower dies 1 and 3 registered as shown in Fig. 1.

By reversing the relation of the upper and lower die blocks shown in Fig. 12, so that the upper die block is moved a corresponding distance to the left, instead of to the right, as shown in said figure, a larger drill blade, and a forged twist drill somewhat larger in diameter will be formed, than when the upper and lower dies 1 and 3 register as illustrated in Fig. 1.

In some cases we may out off all the flash? ing and not use any lands. Such constructions are shown in Fig. 10 and Fig. 11.

Having thus described this invention in 

